Numerous grading machines are known in the prior art. An example of a motor-driven grading machine is illustrated in U.S. Pat. No. 3,776,318 issued to Layton on Dec. 4, 1973. The machine illustrated in the '318 patent utilizes a grader or scraper blade means carried by a motor-driven vehicle. The blade means includes a pair of blade sections disposed end-to-end and pivotably connected at their adjacent ends. The blade sections can thus be pivoted to produce either a crown or a valley in the area being worked.
An example of a towed grading machine is disclosed in U.S. Pat. No. 3,608,643 issued to Flood et al on Sept. 28, 1971. The grading machine illustrated in the '643 patent utilizes a grading blade pivotably attached to a frame about a vertical axis. A pair of laterally spaced wheels are connected to the blade through short beams which are connected to the blade through horizontal and vertical pivots. Separate hydraulic piston and cylinder devices are provided for turning the grading blade about its vertical pivot axis to adjust the angular disposition of the grading blade and for pivoting the short wheel carrying beams about their horizontal and vertical pivots to thereby adjust the height of the blade and steer the grader. Tilting of the grading blade is mentioned, however, no mechanism for accomplishing this function is disclosed.
Other towed grading machines are illustrated in U.S. Pat. No. 2,142,985 issued to Arndt on Jan. 10, 1939; U.S. Pat. No. 2,197,390 issued to Arndt on Apr. 16, 1940; U.S. Pat. No. 3,376,937 issued to Groberg on Apr. 9, 1968; and U.S. Pat. No. 3,428,133 issued to Young et al on Feb. 18, 1969.